arXiv subjects

Gerardo F. Goya

Publications and source records attributed to Gerardo F. Goya.

16 recordsLinked to original sources

arXiv2025

Magnetically Enhanced Fenton-Like Processes by Nanofibers: Real-Time Observation of Tetracycline Degradation in Pig Manure Wastewater

This study presents a novel approach for the degradation of tetracycline (TC) in pig manure wastewater using magnet-ite-based magnetic nanofibers (MNFs) as heterogeneous Fenton-like catalysts. The MNFs, composed of polyacrylonitrile (PAN) embedded with MnFe_2O_4 nanoparticles, were synthesized via electrospinning and exhibited high stability and catalytic efficiency. The degradation process was driven by hydroxyl radical (OH) formation through hydrogen peroxide (H2O2) activation on the MNF surface. The results showed that TC was first adsorbed onto the MNFs before undergoing oxidation, with treatment efficiency increasing with H2O2 concentration up to an optimum point, due to increased OH scavenging by H_2O_2. A heterogeneous dynamic kinetic model (DKM) was developed to describe the degradation mechanism, incorporating reactive oxygen species (ROS) generation, catalyst surface inactivation, and polymer strip-ping effects. Furthermore, the application of an alternating magnetic field significantly accelerated the reaction rate, likely due to localized heating effects. This study highlights the potential of MNFs as a scalable, reusable and efficient alternative for antibiotic-contaminated wastewater treatment, offering advantages over conventional homogeneous Fenton processes by minimizing iron sludge formation and broadening the operational pH range.

physics.chem-ph↗

arXiv2024

Novel Cisplatin-Magnetoliposome Complex Shows Enhanced Antitumor Activity via Hyperthermia

There are several methods to improve cancer patient survival rates by inducing hyperthermia in tumor tissues, which involves raising their temperature above 41°C. These methods utilize different energy sources to deliver heat to the target region, including light, microwaves or radiofrequency electromagnetic fields. We have developed a new, magnetically responsive nanocarrier, consisting of liposomes loaded with magnetic nanoparticles and cis-diamminedichloroplatinum (II) (CDDP), commonly known as Cisplatin. The resulting magnetoliposome (ML) is rapidly internalized by lung and pancreas tumor cell lines, stored in intracellular vesicles, and capable of inducing hyperthermia under magnetic fields. The ML has no significant toxicity both in vitro and in vivo and, most importantly, enhances cell death by apoptosis after magnetic hyperthermia. Remarkably, mice bearing induced lung tumors, treated with CDDP-loaded nanocarriers and subjected to an applied electromagnetic field, showed an improved survival rate over those treated with either soluble CDDP or hyperthermia alone. Therefore, our approach of magnetic hyperthermia plus CDDP-ML significantly enhances in vitro cell death and in vivo survival of treated animals.

q-bio.TO↗

arXiv2024

Disruption of the mitochondrial network in a mouse model of Huntington's disease visualized by in tissue multiscale 3D electron microscopy

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by an expanded CAG repeat in the coding sequence of the huntingtin protein. Initially, it predominantly affects medium-sized spiny neurons (MSSNs) of the corpus striatum. No effective treatment is available, thus urging the identification of potential therapeutic targets. While evidence of mitochondrial structural alterations in HD exists, previous studies mainly employed 2D approaches and were performed outside the strictly native brain context. In this study, we adopted a novel multiscale approach to conduct a comprehensive 3D in situ structural analysis of mitochondrial disturbances in a mouse model of HD. We investigated MSSNs within brain tissue under optimal structural conditions utilizing state-of-the-art 3D imaging technologies, specifically FIB/SEM for the complete imaging of neuronal somas and Electron Tomography for detailed morphological examination and image processing-based quantitative analysis. Our findings suggest a disruption of the mitochondrial network towards fragmentation in HD. The network of interlaced, slim, and long mitochondria observed in healthy conditions transforms into isolated, swollen, and short entities, with internal cristae disorganization, cavities, and abnormally large matrix granules.

q-bio.SC↗

arXiv2024

Remote-Controlled Activation of the Release through Drug-Loaded Magnetic Electrospun Fibers

The integration of magnetic nanoparticles within fibrillar structures represents an interesting avenue for the remotely controlled release of therapeutic agents. This work presents a novel drug release platform based on electrospun magnetic fibers (EMFs) combining drugs, magnetic nanoparticles (MNPs) and mesoporous silica nanoparticles (MSNs) for controlled drug delivery via alternating magnetic fields (AMF). The platform was demonstrated to be versatile and effective for hydrophilic ketorolac (KET) and hydrophobic curcumin (CUR) encapsulation and the major response observed for AMF-triggered release was reached using drug-loaded MSNs within the fibers, providing fine control over drug release patterns. The EMFs exhibited excellent inductive heating capabilities, showing a temperature increase up to 8 °C within a 5 min AMF pulse. The system is shown to be promising for applications like transdermal pain management, oncological drug delivery, tissue engineering, and wound healing, enabling precise control over drug release in both spatial and temporal dimensions. The findings of this study offer valuable insights into the development of the next generation of smart drug delivery systems, based in multifunctional materials that can be remotely regulated and potentially revolutionize the field of nanomedicine.

cond-mat.mtrl-sci↗

arXiv2024

Effect of temperature and copper doping on the heterogeneous Fenton-like activity of Cu$_x$Fe$_{3-x}$O$_4$ nanoparticles

Ferrite nanoparticles serve as potent heterogeneous Fenton-like catalysts, producing reactive oxygen species (ROS) for decomposing organic pollutants. We investigated the impact of temperature and copper content on the catalytic activity of nanoparticles with different oxidation states of iron. Via solvothermal synthesis, we fabricated copper-doped magnetite (Cu$_x$Fe$_{3-x}$O$_4$) with a Fe$^{2+}$/Fe ratio ~0.33 for the undoped system. Using a microwave-assisted method, we produced copper-doped oxidized ferrites, yielding a Fe$^{2+}$/Fe ratio of ~0.11 for the undoped nanoparticles. The ROS generated by the catalyst were identified and quantified by electron paramagnetic resonance, while optical spectroscopy allowed us to evaluate its effectiveness for the degradation of a model organic dye. At room temperature, the magnetite nanoparticles exhibited the most $\cdot$OH radical production and achieved almost 90% dye discoloration in 2 hours. This efficiency decreased with increasing Cu concentration, concurrently with a decrease in $\cdot$OH generation. Conversely, above room temperature, Cu-doped nanoparticles significantly enhance the dye degradation, reaching 100% discoloration at 90$^\circ$C. This enhancement is accompanied by a systematic increase in the kinetic constants, obtained from reaction equations, with Cu doping. This study highlights the superior stability and high-temperature catalytic advantages of copper ferrite holding promise for enhancing the performance of nanocatalysts for decomposing organic contaminants.

cond-mat.mtrl-sci↗

arXiv2024

Magnetic Nanoparticles for Neural Engineering

Magnetic nanoparticles (MNPs) are the foundation of several new strategies for neural repair and neurological therapies. The fact that a remote force can act on MNPs at the cytoplasmic space constitutes the essence of many new neurotherapeutic concepts. MNPs with a predesigned physicochemical characteristic can interact with external magnetic fields to apply mechanical forces in definite areas of the cell to modulate cellular behaviour. Magnetic actuation to direct the outgrowth on neurons after nerve injury has already demonstrated the therapeutic potential for neural repair. When these magnetic cores are functionalized with molecules such as nerve growth factors or neuroprotective molecules, multifunctional devices can be developed. This chapter will review some of these new nanotechnology-based solutions for neurological diseases, specifically those based on the use of engineered MNPs used for neuroprotection and neuroregeneration. These include the use of MNPs as magnetic actuators to guide neural cells, modulate intracellular transport and stimulate axonal growth after nerve injury.

q-bio.NC↗

arXiv2023

Magnetic nanofibers for remotely triggered catalytic activity applied to the degradation of organic pollutants

This work reports on the synthesis and characterization of a new type of electrospun magnetic nanofibers (MNFs), and their application for degradation of organic pollutants using remote magnetic inductive heating. We describe a simple protocol combining a fast (app. 5 min) synthesis of MnFe\textsubscript{2}O\textsubscript{4} magnetic nanoparticles (MNPs) by sonochemical route, optimized for inductive heating, with their subsequent incorporation in electrospun MNFs composed of polyacrylonitrile (PAN) nanofibers. The resulting multifunctional MNFs (average diameter $ϕ= 760 \pm 150$ nm) contain up to $\approx 30%$wt. of the MNPs. The composite showed superhydrophobic behaviour ($θ_c = 165^\circ$) and a band gap value of 1.75 eV. We found that the presence of MNPs embedded into the polymeric nanofibers modify the exothermic and the glass transitions temperatures compared with pure PAN nanofibers, suggesting a strong attachment between MNPs and polymeric chains. The MNFs could be remotely activated by alternating magnetic fields (AMF, $f = 200-800$ kHz, $H_0 = 10-36$ kA/m) for accelerating the catalytic reactions of the organic dye methylene blue (MB). A remarkable stability of the MNFs against degradation under extreme pH conditions ($3 80%$ in the presence of hydrogen peroxide under AMFs, attributed to Fe\textsuperscript{2+}/\textsuperscript{3+} and Mn\textsuperscript{2+}/\textsuperscript{3+}/\textsuperscript{4+} active centers on the surface of the MNP/MNFs observed from XPS data. The capacity of these materials for magnetic remote activation appeals catalytic applications under conditions of darkness or restrained access, where no photocatalytic reactions can be achieved.

physics.app-ph↗

arXiv2021

Magnetic hyperthermia experiments with magnetic nanoparticles in clarified butter oil and paraffin: a thermodynamic analysis

In Specific Power Absorption (SPA) models for Magnetic Fluid Hyperthermia (MFH) experiments, the magnetic relaxation time of the nanoparticles (NPs) is known to be a fundamental descriptor of the heating mechanisms. The relaxation time is mainly determined by the interplay between the magnetic properties of the NPs and the rheological properties of NPs environment. Although the role of magnetism in MFH has been extensively studied, the thermal properties of the NPs medium and their changes during of MFH experiments have been so far underrated. Here, we show that ZnxFe3-xO4 NPs dispersed through different with phase transition in the temperature range of the experiment: clarified butter oil (CBO) and paraffin. These systems show non-linear behavior of the heating rate within the temperature range of the MFH experiments. For CBO, a fast increase at $306 K$ associated to changes in the viscosity (\texteta(T)) and specific heat (c_p(T)) of the medium below and above its melting temperature. This increment in the heating rate takes place around $318 K$ for paraffin. Magnetic and morphological characterizations of NPs together with the observed agglomeration of the nanoparticles above $306 K$ indicate that the fast increase in MFH curves could not be associated to a change in the magnetic relaxation mechanism, with Néel relaxation being dominant. In fact, successive experiment runs performed up to temperatures below and above the CBO melting point resulted in different MFH curves due to agglomeration of NPs driven by magnetic field inhomogeneity during the experiments. Similar effects were observed for paraffin. Our results highlight the relevance of the NPs medium's thermodynamic properties for an accurate measurement of the heating efficiency for in vitro and in vivo environments, where the thermal properties are largely variable within the temperature window of MFH experiments.

cond-mat.mtrl-sci↗

arXiv2020

Low Dimensional Assemblies of Magnetic MnFe$_2$O$_4$ Nanoparticles and Direct In Vitro Measurements of Enhanced Heating Driven by Dipolar Interactions: Implications for Magnetic Hyperthermia

Magnetic fluid hyperthermia (MFH), the procedure of raising the temperature of tumor cells using magnetic nanoparticles (MNPs) as heating agents, has proven successful in treating some types of cancer. However, the low heating power generated under physiological conditions makes necessary a high local concentration of MNPs at tumor sites. Here, we report how the in vitro heating power of magnetically soft MnFe$_2$O$_4$ nanoparticles can be enhanced by intracellular low-dimensional clusters through a strategy that includes: a) the design of the MNPs to retain Néel magnetic relaxation in high viscosity media, and b) culturing MNP-loaded cells under magnetic fields to produce elongated intracellular agglomerates. Our direct in vitro measurements demonstrated that the specific loss power (SLP) of elongated agglomerates ($SLP=576\pm33$ W/g) induced by culturing BV2 cells in situ under a dc magnetic field was increased by a factor of 2 compared to the $SLP=305\pm25$ W/g measured in aggregates freely formed within cells. A numerical mean-field model that included dipolar interactions quantitatively reproduced the SLPs of these clusters both in phantoms and in vitro, suggesting that it captures the relevant mechanisms behind power losses under high-viscosity conditions. These results indicate that in situ assembling of MNPs into low-dimensional structures is a sound possible way to improve the heating performance in MFH.

cond-mat.soft↗

arXiv2016

Magnetic hyperthermia enhances cell toxicity with respect to exogenous heating

Magnetic hyperthermia is a new type of cancer treatment designed for overcoming resistance to chemotherapy during the treatment of solid, inaccessible human tumors. The main challenge of this technology is increasing the local tumoral temperature with minimal side effects on the surrounding healthy tissue. This work consists of an in vitro study that compared the effect of hyperthermia in response to the application of exogenous heating (EHT) sources with the corresponding effect produced by magnetic hyperthermia (MHT) at the same target temperatures. Human neuroblastoma SH-SY5Y cells were loaded with magnetic nanoparticles (MNPs) and packed into dense pellets to generate an environment that is crudely similar to that expected in solid micro-tumors, and the above-mentioned protocols were applied to these cells. These experiments showed that for the same target temperatures, MHT induces a decrease in cell viability that is larger than the corresponding EHT, up to a maximum difference of approximately 45\% at T = 46°C. An analysis of the data in terms of temperature efficiency demonstrated that MHT requires an average temperature that is 6°C lower than that required with EHT to produce a similar cytotoxic effect. An analysis of electron microscopy images of the cells after the EHT and MHT treatments indicated that the enhanced effectiveness observed with MHT is associated with local cell destruction triggered by the magnetic nano-heaters. The present study is an essential step toward the development of innovative adjuvant anti-cancer therapies based on local hyperthermia treatments using magnetic particles as nano-heaters.

q-bio.TO↗

arXiv2013

Magnetic Hyperthermia with Fe3O4 nanoparticles: the Influence of Particle Size on Energy Absorption

We have studied the magnetic and power absorption properties of a series of magnetic nanoparticles (MNPs) of Fe3O4 with average sizes ranging from 3 to 26 nm. Heating experiments as a function of particle size revealed a strong increase in the specific power absorption (SPA) values for particles with = 25-30 nm. On the other side saturation magnetization MS values of these MNPs remain essentially constant for particles with above 10 nm, suggesting that the absorption mechanism is not determined by MS. The largest SPA value obtained was 130 W/g, corresponding to a bimodal particle distribution with average size values of 17 and 26 nm.

cond-mat.mtrl-sci↗

arXiv2012

Influence of the substrate and precursor on the magnetic and magneto-transport properties in magnetite films

We have investigated the magnetic and transport properties of nanoscaled Fe3O4 films obtained from Chemical Vapor Deposition (CVD) technique using [FeIIFe2III(OBut)8] and [Fe2III(OBut)6] precursors. Samples were deposited on different substrates (i.e., MgO (001), MgAl2O4 (001) and Al2O3 (0001)) with thicknesses varying from 50 to 350 nm. Atomic Force Microscopy analysis indicated a granular nature of the samples, irrespective of the synthesis conditions (precursor and deposition temperature, Tpre) and substrate. Despite the similar morphology of the films, magnetic and transport properties were found to depend on the precursor used for deposition. Using [FeIIFe2III(OBut)8] as precursor resulted in lower resistivity, higher MS and a sharper magnetization decrease at the Verwey transition (TV). The temperature dependence of resistivity was found to depend on the precursor and Tpre. We found that the transport is dominated by the density of antiferromagnetic antiphase boundaries (AF-APB's) when [FeIIFe2III(OBut)8] precursor and Tpre = 363 K are used. On the other hand, grain boundary-scattering seems to be the main mechanism when [Fe2III(OBut)6] is used. The Magnetoresistance (MR(H)) displayed an approximate linear behavior in the high field regime (H > 796 kA/m), with a maximum value at room-temperature of \sim2-3% for H = 1592 kA/m, irrespective from the transport mechanism.

cond-mat.mtrl-sci↗

arXiv2011

Magnetic Field-Assisted Gene Delivery: Achievements and Therapeutic Potential

The discovery in the early 2000's that magnetic nanoparticles (MNPs) complexed to nonviral or viral vectors can, in the presence of an external magnetic field, greatly enhance gene transfer into cells has raised much interest. This technique, called magnetofection, was initially developed mainly to improve gene transfer in cell cultures, a simpler and more easily controllable scenario than in vivo models. These studies provided evidence for some unique capabilities of magnetofection. Progressively, the interest in magnetofection expanded to its application in animal models and led to the association of this technique with another technology, magnetic drug targeting (MDT). This combination offers the possibility to develop more efficient and less invasive gene therapy strategies for a number of major pathologies like cancer, neurodegeneration and myocardial infarction. The goal of MDT is to concentrate MNPs functionalized with therapeutic drugs, in target areas of the body by means of properly focused external magnetic fields. The availability of stable, nontoxic MNP-gene vector complexes now offers the opportunity to develop magnetic gene targeting (MGT), a variant of MDT in which the gene coding for a therapeutic molecule, rather than the molecule itself, is delivered to a therapeutic target area in the body. This article will first outline the principle of magnetofection, subsequently describing the properties of the magnetic fields and MNPs used in this technique. Next, it will review the results achieved by magnetofection in cell cultures. Last, the potential of MGT for implementing minimally invasive gene therapy will be discussed.

q-bio.QM↗

arXiv2011

Magnetically-triggered Nanocomposite Membranes: a Versatile Platform for Triggered Drug Release

Drug delivery devices based on nanocomposite membranes containing thermoresponsive nanogels and superparamagnetic nanoparticles have been demonstrated to provide reversible, on-off drug release upon application (and removal) of an oscillating magnetic field. The dose of drug delivered can be tuned by engineering the phase transition temperature of the nanogel, the loading of nanogels in the membrane, and the membrane thickness, allowing for the delivery of drugs over several orders of magnitude of release rates. The zero-order kinetics of drug release through the membranes permit drug doses from a specific device to be tuned according to the duration of the magnetic field. Drugs over a broad range of molecular weights (500-40,000 Da) can be delivered by the same membrane device. Membrane-to-membrane and cycle-to-cycle reproducibility is demonstrated, suggesting the general utility of these membranes for drug delivery.

cond-mat.mtrl-sci↗

arXiv2011

A Magnetically-Triggered Composite Membrane for On-Demand Drug Delivery

Nanocomposite membranes based on thermosensitive, poly(N-isopropylacrylamide)-based nanogels and magnetite nanoparticles have been designed to achieve "on-demand" drug delivery upon the application of an oscillating magnetic field. On-off release of sodium fluorescein over multiple magnetic cycles has been successfully demonstrated using prototype membrane-based devices. The total drug dose delivered was directly proportional to the duration of the "on" pulse. The membranes were non-cytotoxic, biocompatible, and retained their switchable flux properties after 45 days of subcutaneous implantation.

cond-mat.mtrl-sci↗

arXiv2011

Magnetic Interactions in Ball-Milled Spinel Ferrites

Spinel Fe3O4 nanoparticles have been produced through ball milling in methyl-alcohol (CH3OH), aiming to obtain samples with similar average particle sizes and different interparticle interactions. Three samples having Fe3O4/CH3(OH) mass ratios R of 3 %, 10 % and 50 % wt. were milled for several hours until particle size reached a steady value ( ~ 7-10 nm). A detailed study of static and dynamic magnetic properties has been undertaken by measuring magnetization, ac susceptibility and Mössbauer data. As expected for small particles, the Verwey transition was not observed, but instead superparamagnetic (SPM) behavior was found with transition to a blocked state at TB ~ 10-20 K. Spin disorder of the resulting particles, independent of its concentration, was inferred from the decrease of saturation magnetization MS at low temperatures. For samples having 3% wt. of magnetic particles, dynamic ac susceptibility measurements show a thermally activated Arrhenius dependence of the blocking temperature with applied frequency. This behaviour is found to change as interparticle interactions begin to rule the dynamics of the system, yielding a spin-glass-like state at low temperatures for R = 50 wt.% sample.

cond-mat.mtrl-sci↗